<template>
  <div>
    <!-- 商品分类导航 -->
    <div class="type-nav">
      <div class="container">
        <div @mouseleave="leaveshow" @mouseenter="showenter">
          <h2 class="all">全部商品分类</h2>
          <transition name="sort">
            <div class="sort" v-show="show">
              <div class="all-sort-list2" @click="getSearch">
                <div
                  class="item"
                  v-for="(c1,index) in categoryList.slice(0,16)"
                  :key="c1.categoryId"
                  :class="{cur:currentIndex==index}"
                >
                  <h3 @mouseenter="changeIndex(index)">
                    <a
                      :data-categoryName="c1.categoryName"
                      :data-category1Id="c1.categoryId"
                    >{{c1.categoryName}}</a>
                  </h3>
                  <div
                    class="item-list clearfix"
                    :style="{display:currentIndex==index?'block':'none'}"
                  >
                    <div class="subitem">
                      <dl class="fore" v-for="(c2,index) in c1.categoryChild" :key="c2.categoryId">
                        <dt>
                          <a
                            :data-categoryName="c2.categoryName"
                            :data-category2Id="c2.categoryId"
                          >{{c2.categoryName}}</a>
                        </dt>
                        <dd>
                          <em v-for="(c3,index) in c2.categoryChild" :key="c3.categoryId">
                            <a
                              :data-categoryName="c3.categoryName"
                              :data-category3Id="c3.categoryId"
                            >{{c3.categoryName}}</a>
                          </em>
                        </dd>
                      </dl>
                    </div>
                  </div>
                </div>
              </div>
            </div>
          </transition>
        </div>
        <nav class="nav">
          <a href="###">服装城</a>
          <a href="###">美妆馆</a>
          <a href="###">尚品汇超市</a>
          <a href="###">全球购</a>
          <a href="###">闪购</a>
          <a href="###">团购</a>
          <a href="###">有趣</a>
          <a href="###">秒杀</a>
        </nav>
      </div>
    </div>
  </div>
</template>

<script>
import { mapState } from 'vuex'
import throttle from 'lodash/throttle'
export default {
  name: 'TypeNav',
  data() {
    return {
      //存储用户鼠标移上的id
      currentIndex: -1,
      show: true,
    }
  },
  methods: {
    //鼠标进入修改响应式数据currentIndex属性

    changeIndex: throttle(function (index) {
      this.currentIndex = index
    }, 50),
    getSearch(event) {
      //最好的解决方案：编程式导航 + 事件委派
      //利用事件委派存在一些问题：事件委派，是把全部的子节点【h3、dt、dl、em】的事件委派给父亲结点
      //点击a标签的时候，才会进行路由跳转【怎么确定点击的一定是a标签】
      //存在另一个问题:即使你能确定点击的是a标签，如何区分是一级，还是二级，三级分类标签

      //第一个问题：把子节点当中a标签，我加上自定义属性data-categoryName，其余节点没有
      let element = event.target

      //获取到当前出发这个事件的节点【h3,a,dt,dl】，需要带有data-categoryname这样的节点【一定是a标签】
      let { categoryname, category1id, category2id, category3id } =
        element.dataset
      //如果标签身上拥有categoryname一定是a标签
      if (categoryname) {
        let location = { name: 'search' }
        let query = { categoryName: categoryname }
        //一级分类，二级分类，三级分类的a标签

        if (category1id) {
          query.category1Id = category1id
        } else if (category2id) {
          query.category2Id = category2id
        } else if (category3id) {
          query.category3Id = category3id
        }

        //判断：如果路由跳转的时候，带有params参数，捎带传递过去
        if (this.$route.params) {
          location.params = this.$route.params
          //动态给location配置对象添加query属性
          location.query = query
          //路由跳转
          this.$router.push(location)
        }
      }
    },
    showenter() {
      if (this.$route.path != '/home') {
        this.show = true
      }
    },
    leaveshow() {
      if (this.$route.path != '/home') {
        this.show = false
      }
      this.currentIndex = -1
    },
  },
  //组件挂载完毕：可以向服务器发语请求
  mounted() {
    if (this.$route.path != '/home') {
      this.show = false
    }
  },
  computed: {
    ...mapState({
      //右侧需要的是一个函数，当使用这个计算属性的时候，右侧函数会立即执行一次
      //注入一个参数state，其实即为大仓库的数据
      categoryList: (state) => state.home.categoryList,
    }),
  },
}
</script>

<style scoped lang="less">
.type-nav {
  border-bottom: 2px solid #e1251b;

  .container {
    width: 1200px;
    margin: 0 auto;
    display: flex;
    position: relative;

    .all {
      width: 210px;
      height: 45px;
      background-color: #e1251b;
      line-height: 45px;
      text-align: center;
      color: #fff;
      font-size: 14px;
      font-weight: bold;
    }

    .nav {
      a {
        height: 45px;
        margin: 0 22px;
        line-height: 45px;
        font-size: 16px;
        color: #333;
      }
    }

    .sort {
      position: absolute;
      left: 0;
      top: 45px;
      width: 210px;
      height: 461px;
      position: absolute;
      background: #fafafa;
      z-index: 999;

      .all-sort-list2 {
        .item {
          h3 {
            line-height: 30px;
            font-size: 14px;
            font-weight: 400;
            overflow: hidden;
            padding: 0 20px;
            margin: 0;

            a {
              color: #333;
            }
          }

          .item-list {
            display: none;
            position: absolute;
            width: 734px;
            min-height: 460px;
            background: #f7f7f7;
            left: 210px;
            border: 1px solid #ddd;
            top: 0;
            z-index: 9999 !important;

            .subitem {
              float: left;
              width: 650px;
              padding: 0 4px 0 8px;

              dl {
                border-top: 1px solid #eee;
                padding: 6px 0;
                overflow: hidden;
                zoom: 1;

                &.fore {
                  border-top: 0;
                }

                dt {
                  float: left;
                  width: 54px;
                  line-height: 22px;
                  text-align: right;
                  padding: 3px 6px 0 0;
                  font-weight: 700;
                }

                dd {
                  float: left;
                  width: 415px;
                  padding: 3px 0 0;
                  overflow: hidden;

                  em {
                    float: left;
                    height: 14px;
                    line-height: 14px;
                    padding: 0 8px;
                    margin-top: 5px;
                    border-left: 1px solid #ccc;
                  }
                }
              }
            }
          }
        }
        .cur {
          background: skyblue;
        }
      }
    }

    //过渡动画的样式
    //过渡动画开始状态
    .sort-enter {
      height: 0px;
      // transform: rotate(0deg);
    }
    //过渡动画结束状态
    .sort-enter-to {
      height: 461px;
      // transform: rotate(360deg);
    }
    //定义动画时间、速率
    .sort-enter-active {
      transition: all 0.5s linear;
    }
  }
}
</style>>

</style>